Background: Adolescents and young adults in the United States have high rates of sexually transmitted diseases (STDs) with tremendous adverse consequences on health and health care costs. The proposed project will investigate the relationship of health care utilization, health care behavior, and STD epidemiology using data from Add Health, a national study of 20,000 U.S. adolescents. Waves 1 and 2 of Add health were conducted in 1994-1996 and examined risk behaviors, relationships with peers and parents, interactions with the health care system, and self-reported STDs. In Wave 3 of Add Health, original participants will be re-interviewed and undergo testing for common STDs. Objectives: The proposed study will focus on factors related to interactions with the health care system, specifically acceptance of STD screening, the decision to ascertain STD test results, and follow-through to obtain a complete treatment for three curable STDs: Chlamydia trachomatis (Ct), Neisseria gonorrhea (GC), and, if possible, Trichomonas vaginalis (Tv). We will also develop screening criteria to guide STD testing in non-clinical settings. Finally, we will identify specific health care associated factors that contribute to the excess burden of STDs among certain minority populations. Design and Methods: Wave 3 of Add Health will re-contact, interview, and obtain urine specimens from Wave 1 and 2 participants. Urine specimens will be tested for Ct, GC, and, if possible, Tv. Study participants will be given instructions to obtain the test results by telephone and whether or not participants call for results will be recorded. All participants will positive test results will be re-interviewed 1 month after testing to assess care-seeking behaviors. Analyses: Stratified and repression analyses will be conducted. Screening acceptance, calling for test results, and seeking health care for a positive test will be studied using structural equations modeling with measures of behavioral and normal beliefs, attitudes, expectancies, emotions, and self-efficacy. Logistic regression analysis will be used to develop screening criteria applicable in community settings and to assess specific determinants of race/ethnicity-related differences in prevalence. Significance: This study will identify factors that influence screening acceptance, health care seeking, and health care utilization by young people with or at risk of STDs, thereby creating the basis of more effective interventions to control the continuing epidemic of STDs in young Americans.